NFPA Journal® online exclusive, February 2009
By Rich Duffy, Stan Sanders, Dave Snyder, Jeff Stull, and Grace Stull
Over the past three decades, the positive-pressure self-contained breathing apparatus (SCBA) has become the norm for the fire service, as a steady progression of new features and capabilities improved the protection afforded firefighters. However, the SCBA remains the heaviest and bulkiest part of a firefighter's personal protective equipment ensemble. This shortcoming is about to change.
In the summer of 2008, the Department of Homeland Security (DHS) awarded the International Association of Fire Fighters (IAFF) a contract to commercialize a new form of pressure vessel and soft cover that can replace conventional SCBA cylinders. This will substantially reduce the weight and profile of SCBA and help address SCBA's stress-inducing aspects on firefighters and other first responders. Existing cylinders primarily consist of an aluminum liner wrapped in carbon, Kevlar®, and fiberglass, with operating pressures up to 5,000 psi.
The 15-month effort includes getting the necessary government approvals for the new pressure vessel, working with the SCBA industry to integrate the new pressure vessel as part of existing SCBA; fulfilling the certification requirements of government and the current edition of NFPA 1981, Open-Circuit, Self-Contained Breathing Apparatus for the Fire and Emergency Services; and field testing the vessel. The IAFF, developer Vulcore Industrial LLC (Fort Wayne, Indiana) and research firm, International Personnel Protection, Inc. (Austin, TX) are working with a technical advisory committee consisting of several leading fire departments and other first responder organizations that have extensive experience wearing and servicing SCBA. The project will result in a new pressure array that will be made available to all SCBA manufacturers as an alternative to current cylinders.
The new pressure vessel, developed by Vulcore Industrial LLC of Fort Wayne, Indiana, is based on inner cores of molded, highly specialized, high-temperature plastic called Hytrel, which is made by Dupont. These plastic vessels are braided with a special form of Kevlar to ensure that they can withstand all expected pressures and remain flexible, then wound with pre-impregnated carbon filament. Winding the braided cores with carbon filament provides the overall strength of the pressure vessel.
The cores are essentially two mini-elongated cylinders connected by a flexible tube made of the same plastic as the cylinders themselves. In fact, the entire "two-cell" pressure vessel, including the connector, is created during the same molding process.
A number of prepared cores are laid parallel to each other and provided with fittings to connect to a manifold. The manifold, which includes a valve and pressure gauge, is then connected to a first-stage regulator and other SCBA components.
The 45-minute service-life-rated system will consist of seven two-cell pressure vessels that have an overall depth of approximately 1.9 inches (4.8 centimeters), compared with 7 inches (18 centimeters) on average for conventional SCBA cylinders, and an overall width of about 16 inches (41 centimeters). The expected length of the pressure array is close to 2 feet (61 centimeters). Because of the connections between the two cells (braided but not filament wrapped) and use of a flexible manifold, however, the pressure vessel array can bend both vertically and horizontal to conform to the firefighter's back and maintain a low profile.
When the array is combined with a soft cover and harness assembly, it weighs nearly 50 percent less than SCBA with conventional metal-lined cylinders. Further, unlike current industry SCBA cylinders, there is no fragmentation hazard to the wearer should the vessel rupture. A punctured pressure vessel would simply vent the contained air to the atmosphere with no danger of explosion, as demonstrated by NASA in a series of tests using a variety of projectiles and forces.
Working with the Fort Wayne Fire Department, Vulcore Industrial has tested a prototype that easily outperforms conventional SCBA in obstacle courses and simulated confined space entry evaluations. The prototype has also been tested for several performance attributes. For example, pressure vessels filled with air have shown no air loss after two years. Sample pressure vessels that have been cycled repeatedly in stages of pressurization and depressurization continue to meet industry burst standards.
The new pressure vessel technology has not yet been named, though some call the system the "flat pack" given the drastic change in profile. Not only will the ensemble look different, but it will reduce stress and enhance confined-space mobility. Most important, the new technology will represent a paradigm shift in the industry in the same way that positive-pressure SCBA did when it replaced earlier fire service respirators.
Stan Sanders, chairman and president of Sanders Industrial Design and Vulcore Industrial, is the inventor of the new pressure vessel technology, have been involved in the development of pressure vessels for special applications over the past 40 years.
David Snyder, vice president of Operations & Business Development for Vuclore Industrial, has worked in the business management of both life support system development and production of products used in aerospace, medical and home health care industries.
Jeff Stull and Grace Stull, president and vice president of International Personnel Protection, Inc., provide industry leading research and expertise for personnel protective equipment development and use.
In this Section:
|Fixed Water-Based Firefighting Systems for Road Tunnels
Parson Brinckerhoff undertook a study to evaluate the effectiveness of FFFS for application in tunnel fires.
|The Role of Bomb Technicians in Arson Investigations
While many fire investigators are very good at determining origin and cause, many have little to no experience in dealing with improvised explosive devices (IEDs) and improvised incendiary devices (IIDs).
|Using Computers To Determine Fireworks Safety
In 2008, researchers performed a series of ballistics tests to use in determining appropriate separation distances for fireworks displays.
|The Upcoming Revolution in SCBA Technology
The self-contained breathing apparatus remains the heaviest and bulkiest part of a firefighter’s personal protective equipment ensemble. This shortcoming is about to change.